A typical form of vehicle seat with head support mounted thereon comprises a seat portion or squab and a backrest portion with a head support which is mounted to the upper edge of the backrest portion by a suitable form of connecting arrangement. It will be appreciated that, while that is a generally typical basic configuration for a vehicle seat with a head support, there are many different variations on that theme, resulting in a wide range of different structural configurations.
As the head of a seat occupant is usually disposed at a spacing from the head support of the vehicle seat, it has been found that, in particular with collision impact speeds of up to about 15 kph, there is the danger of the occurrence of the injury usually referred to as whiplash trauma involving a shearing loading being applied to individual cervical vertebrae. In order to at least obviate such whiplash injury, for example DE 296 01 798 U1 has already proposed integrating into the head support of the vehicle seat a structure in the nature of an air bag in order to provide for forward displacement of the head support in relation to the vehicle seat in the event of a collision or impact situation in the tail region of the respective vehicle in which the vehicle seat is fitted. Integrating an arrangement of that kind into the head support however suffers from the disadvantage that the head support is effectively no longer an autonomous or self-contained unit and therefore cannot be easily removed from the backrest of the vehicle seat, or that the shape of the head support is correspondingly influenced or indeed impaired by virtue of the integration of the air bag arrangement.
A vehicle seat having a head support is to be found in DE 197 38 201 A1, including an arrangement whereby, in the event of vigorous acceleration or deceleration in the direction of travel of the vehicle, for example in a collision accident, the head support is automatically inclined forwardly and is locked in that position. In that case the head support can be fixedly connected to at least one support bar, the guide for which has a lower support bar guide element which can be locked in respect of height to the support bar and which is arranged on the backrest carrier structure pivotably about a horizontal axis which is parallel to the backrest carrier structure. In that arrangement an upper support bar guide element can be disposed at a spacing relative to the lower support bar guide element, which carries the support bar displaceably in respect of height and which is arranged on the backrest carrier structure pivotably about a horizontal axis which is parallel to the backrest carrier, wherein the upper support guide bar element is connected to the backrest carrier by way of a pivotable arm which is mounted to the backrest carrier structure and to the upper support bar guide element and which, upon pivotal movement thereof, changes the spacing between the upper support bar guide element and the backrest carrier structure. For pivoting the arm for the purposes of increasing the spacing between the upper support bar guide element and the backrest carrier structure, that arrangement has a device which is responsive to vehicle acceleration or deceleration. That device can be a leaf spring disposed in the region of the buttocks of the person occupying the vehicle seat, in the backrest of the vehicle seat.